The problem of vulnerable road users being caught under and severely injured or even killed by turning vehicles, especially trucks and busses, is well-known and quite a lot of ideas have been conceived and tested in order to prevent such accidents or at least significantly reduce the frequency with which they occur.
Some of the systems tested focus primarily on warning the driver of the vehicle that there is or might be one or more vulnerable road users next to the vehicle and that extra care should be taken before making a turn with the vehicle. Other systems focus on warning the vulnerable road user(s) that the vehicle is or might be about to make a turn and that care should be taken not to get in the way of the turning vehicle.
European patent application EP 1 331 135 A1 and Danish utility model publications DK 96 00307 U3 and DK 2005 00057 U4 all disclose systems of the latter-mentioned type. Basically, all of these disclosed systems relates to arranging extra warning means on the side of the vehicle for emitting visual and/or acoustic warning signals when the ordinary direction indicator of the vehicle is activated. Thus, the purpose of these systems is to direct the attention of the vulnerable road user(s) towards the vehicle next to them.